In view of the rapid development of information communication industries, an explosive increase in the near future is expected in the amount of data such as transaction information and home page data which are transmitted on a communication network typified by the Internet or the like. Further, more and more virus problems and criminals are occurring on the communication network. Consequently, efforts have been made to make logging on the Internet or the like compulsory. On the basis of these present circumstances and expectations, there is a strong demand for an increase in the capacities of information storage apparatuses. However, a hard disk, a kind of mass information storage apparatus to and from which information can be written and read at high speed, requires high costs for extensions. Accordingly, at present, there is no other way but to dispose of information exceeding the capacity of the hard disk. A magnetic tape storage apparatus, a kind of mass information storage apparatus, enables the inexpensive realization of a large capacity exceeding that of hard disks. However, the magnetic tape is a sequential medium to and from which information is sequentially written or read, and thus offers insufficient information I/O speeds. Consequently, at present, the magnetic tape storage apparatus is used only for applications for the longtime storage of information.
The simple storage of a large amount of data is insufficient to deal with the explosive increase in the amount of data expected to occur in the near future. It is desirable in for example, the following fields to inexpensively enable both the storage of a betabyte-scale amount of information and high-speed accesses within several seconds (what is called near-line accesses) in order to secure advanced retrieval capabilities: the field of data mining in which a consumption trend or the like is found out from a large amount of information such as sale information, the field of experimental data analysis in atomic physics, the field of collation techniques using fingerprints or DNA information, the field of patent information retrieval, the field of banks and securities, the field of electronic clinical charts, and the field of IDC (Internet Data Center).
As a high-speed and mass next-generation storage apparatus, an optical information apparatus which stores information using an optical storage medium typified by MO or DVD is gathering much attention instead of the hard disk and magnetic tape, which have the above disadvantages. The optical information storage apparatus enables information to be read or written at high speed and is expected to offer a drastically increased capacity in the near future as a result of technical renovations such as development of blue laser diodes or surface recording systems. It is also expected to realize a storage capacity comparable to that of the magnetic tape storage apparatus.
A possible next-generation optical information storage apparatus has, for example, a magazine that stores optical storage media, a drive that writes or reads information to or from an optical storage medium, and a changer that moves the optical storage medium between the magazine and the drive, the three components being compactly housed in a housing. If such an optical information storage apparatus is realized, the capacity can be easily increased by increasing the number of optical storage media or arranging optical information storage apparatuses. Moreover, maintenance can be easily carried out by detaching or replacing the multiple magazines and optical storage media arranged in the housing.
For the above next-generation optical information storage apparatus, an optical storage medium on which a read or write operation has been completed needs to be reliably replaced, within a small area, with a new one stored in the magazine. This technique is described, for example, in Patent Documents 1 and 2 in conjunction with a disk auto changer that realizes the precise delivery of disks, in Patent Documents 3 and 4 in conjunction with a disk auto changer having a reduced apparatus size, and in Patent Document 5 in conjunction with a disk changer apparatus having a reduced apparatus size and which realizes the precise delivery of disks.
(Patent Document 1)
Japanese Patent Laid-Open No. 9-282770
(Patent Document 2)
Japanese Utility Model Laid-Open No. 3055247
(Patent Document 3)
Japanese Patent Laid-Open No. 9-82010
(Patent Document 4)
Japanese Patent Laid-Open No. 8-45164
(Patent Document 5)
Japanese Patent Laid-Open No. 10-27408
However, an object of such an optical information storage apparatus as described above is considered to access, at high speed, information dividedly stored in multiple optical storage media as if the information were recorded in a single storage medium. To achieve this object, it is necessary to quickly replace an optical storage medium on which a read or write operation has been completed with one on which the next write or read operation is to be performed. However a technique realizing such replacement is not yet known.